1. 1
WAVES

2. 1) Recognize that all waves transfer energy.
2) Explain the Doppler Effect in terms of everyday interactions.
5) Compare and contrast the characteristics of electromagnetic and mechanical (sound)
waves.
3) Relate frequency & wavelength to the energy of different types of electromagnetic waves & mechanical waves.
6) Explain the phenomena of reflection, refraction, interference, & diffraction.
4) Relate the speed of sound to different mediums. 2

3. 3
Waves
Waves are disturbances that carry energy through matter or space. Clip
Waves can be visible or invisible evidence of energy transfer.
The material does not actually travel with the wave….. only the energy is carried.

4. Types of Waves Two types of waves:4
Two types of waves:
Mechanical
Non-Mechanical
Mechanical: waves need a medium in order to travel.
Examples: Sound, water
Non-mechanical: waves do not need a medium to travel.
Examples: light, gamma waves, microwaves, x-rays

5. 5
Mechanical Waves
Waves that require a medium to travel.
A medium is the material a wave travels through (solid, liquid, gas, vacuum)
Sound and water.
Light waves are NOT Mechanical Waves.

6. Ways that waves travel Transverse waves (left box)6
Ways that waves travel
Transverse waves (left box)
Water, light
Compressional waves (right box)
AKA: Longitudinal Waves
sound

7. Transverse Waves Transverse waves are UP & DOWN movements.7
Transverse Waves
Transverse waves are UP & DOWN movements.
The displacement of individual particles is perpendicular (at right angles) to the direction of the wave.
EX: water waves, radio waves (all EM waves)

8. Describing a Transverse Wave8
Describing a Transverse Wave

9. Movement of a Transverse Wave11 9
Movement of a Transverse Wave
CLIP

10. Remember: Energy is transferred ----NOT THE MATTER!--12
Example - Water
Remember: Energy is transferred ----NOT THE MATTER!--

11. Compressional Waves 13
Compressional waves are a series of PUSHES & PULLS in which the motion of the medium is in the same direction as the wave
Ex. Sound Waves

12. Parts of a Compressional Wave15
Compressions & Rarefactions
Rarefaction is a place where the atmospheric pressure is lowest- molecules are spread out (behind the compression).

13. Characteristics of a Compressional Wave14

14. Energy moves this way

15. Wavelength of Transverse and Compressional Waves
Comparison

16. Amplitude of Compressional Wave
Tighter compressions=Higher amplitude=Higher Energy

17. Transverse Waves

18. Compressional Waves

19. Concept Check
Light (EM waves)….
is a mechanical wave or a non-mechanical wave
travels as a transverse wave or a compressional wave
Sound.….
is a mechanical wave or a non-mechanical wave
travels as a transverse wave or acompressional wave

20. The higher the amplitude, the more energy the wave is carrying 9
amplitude
The higher the amplitude, the more energy the wave is carrying
In a compressional wave- it’s how tightly the compressions are.

21. Frequency Number of waves per second.10
Number of waves per second.
How many waves pass a certain point every sec.
Unit: Hertz
1 wave per second= 1 Hz

22. λ Wavelength Wavelength10 λ
Wavelength
Distance between two identical points on adjacent waves.
Measured in Meters
As the wavelength decreases,…
the frequency increases

23. Speed of a wave ν = f λ ν is the velocity (m/s)
16.1
Speed of a wave
ν = f λ
ν is the velocity (m/s)
f is the frequency (hertz)
λ is the wavelength (m)
The speed of a mechanical waves is constant for any given medium..
The speed of a wave changes as it moves through different media

24. Let’s do some practice problems.
16.2
ν = f xλ
Let’s do some practice problems.

25. Wave interactions with matter

26. Wave interactions with matter17
Wave interactions with matter
Reflection occurs when a wave hits another wave or object that it cannot pass through and bounces back.

27. Law of Reflection

28. Refraction occurs when a wave passes from one medium to another at an angle and bends (changes direction) due to a change in speed. 18

29. Refraction

30. 19
Diffraction occurs when a wave passes through an opening and spreads out
Diffraction is a wave phenomenon that is dependent on wavelength
Light waves bend as they pass by the edge of a narrow aperture or slit 

31. Diffraction

32. When a wave encounters an obstacle.
Apparent bending of waves around small obstacles and the spreading out of waves past small openings.

33. 20
Constructive Interference occurs when two or more waves hit the same point and combine to produce a larger single wave.

34. 20
Destructive Interference occurs when two or more waves hit the same point and combine to produce a smaller single wave.

35. Constructive Interference
Clip
Constructive Interference
Destructive Interference

36. Two waves interfering with each other… constructively and destructively.

37. Concept Check B A
1)Which waves has a higher amplitude?
2) Which light wave will go faster?
a) light traveling in a vacuum
b) light traveling in glass
3) What is causing the rainbow of colors to appear from the prism?

38. Review of Waves
Properties of Mechanical Waves-video clip

39. Review of Waves

40. Review of Waves

41. GOALS REVISITED. Recognize that all waves transfer energy.
Explain the phenomena of reflection, refraction, interference, & diffraction.
Relate frequency & wavelength to the energy of different types of electromagnetic waves & mechanical waves.
GOALS REVISITED.
Relate the speed of sound to different mediums.
Explain the Doppler Effect in terms of everyday interactions.
Compare and contrast the characteristics of electromagnetic and mechanical (sound)
waves. 2